Physics Explains How a Long Jumper Leaped So Far He Almost Cleared the Pit
It isn't just about speed.
What were you doing when you were 19? Chances are, you weren’t breaking a 23-year-old world long jump record like Juan Miguel Echevarria. At the international Diamond League competition in Stockholm on Sunday, the Cuban long jumper leaped so far he almost cleared the sand pit, showcasing not only incredible athleticism but an uncanny ability to manipulate physics.
It was hardly important that a slight tailwind — at 2.1 meters per second, just 0.1 meters per second faster than official rules permit — disqualified his jump distance from record purposes. By completing a jump of 29 feet, 11.5 inches (8.83 meters), Echevarria blew away Jeff Henderson of the United States, who came in second place with a jump of 27 feet and 6 inches (8.39 meters). It’s clear from the video below that the lanky Echevarria approached the board — the piece of wood marking the point where a jumper should take off — with immense speed, but as sports scientists have pointed out previously, speed is just one component of a perfect long jump.
The late Melvin Ramey, Ph.D., a biochemist and engineer working with USA Track and Field, explained the physics of the perfect long jump in a video for the National Science Foundation in 2012. “The human body becomes a projectile,” he explained.
For a human (or any projectile) to reach its maximum trajectory, it must maximize its projectile motion, which in turn can be broken down into its horizontal velocity (the speed at which it’s moving along the runway) and its vertical velocity (its speed at liftoff). But the distance that it travels is ultimately decided by its launch angle — the angle that, in this case, Echevarria jumps when he hits the board.
It might at first make sense that a 45° angle — halfway between jumping perfectly straight into the air (90°) and not jumping at all (0°) — would make for the farthest trajectory, but this isn’t the case because gravity acts on vertical velocity, pulling the jumper downward. According to Ramey, world-class jumps have a launch angle of 18° to 22°. The trick, he explains, is jumping in a way that allows the athlete to maintain velocity once leaving the board.
This video illustrates how launch angle would affect trajectory in a vacuum.
There are, of course, other forces to consider. Wind speed can give a jumper’s horizontal or vertical velocity a boost, depending on its direction. Air drag can also make a big difference, which is why long jumps in high-altitude regions, like the Alps, are judged differently than jumps closer to sea level, where the air is denser.
Haters could argue that Echevarria was helped out by the relatively thin air in Stockholm and the 2.1 meter per second backwind, but there’s no doubting his pure athleticism. The amount of strength and speed it requires to launch yourself into the air — even if you get the launch angle just right — and ability to absorb all the stress of jumping and landing is impressive indeed. In a video for the Wall Street Journal in 2017, Phil Cheetham, a senior sport technician for the U.S. Olympic Committee, explained that long jumpers usually reach a speed of 10 to 12 meters per second when coming down the runway, and at liftoff, they feel a force equivalent to 15 times their body weight.
Echevarria may not have set an official record with this jump, but he broke his own personal best outdoor record, which he set in Rome earlier this year with a jump of 27.76 feet (8.46 meters).
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